Electrical measuring instrument.



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Patented Oct. l, |90I.

N. H. SUREN.

ELECTRICAL MEASURING INSTRUMENT.

\App11cat1on filed Feb 16, 1901 O ffl UNITED STATES PATENT OFFICE.

NATHAN H. SUREN, OF NEEDHAM, MASSACHUSETTS, ASSIGNOR TO GAME- l TVELLFIRE ALARM TELEGRAPH COMPANY, OF NEW YORK, Y.

ELECTRICAL. MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent N o. 683,668, dated October1, 1901.

Application iiled February 16, 1901. Serial No. 47,585. (N model.)

To all whom, t may concern:

Be it known that I, NATHAN H. SUREN, of Needham, county of Norfolk,State of Massachusetts, have invented an Improvement in ElectricalMeasuring Instruments, of which the following description, in connectionwith the accompanying drawings, is aspeciiication, like letters on thedrawings representing like parts.

This invention relates to electric-currentmeasuring instruments, and hasfor its object to provide means for regulating the magnetic fieldcontaining the magnetized needle and the conducting-coils which areconnected with the wire carrying the current to be measured, whereby themovements of the pointer may be better controlled, and also to improveand simplify the construction of the instrument in several particulars.

The current-m easurin g instrument in which my invention is embodiedcomprises, essentially, a permanent magnet, a magnetized needlecontained in the magnetic field of said permanent magnet and carryingthe pointer, and two conducting-coils of wire adapted to be connectedwith the Wire carrying the current to be measured, mounted on suitablecores and also contained in the magnetic field of said permanent magnet,said coilsbe- 3o ing disposed at right angles to the lines of force ofthe permanent magnet. In accords ance with this invention the poles'ofthe permanent magnet are bridged together by two magnetic conductors,which form an inclon sure for the coils and the needle, there being onemagnetic conductor on each side oit' the needle, and said magneticconductors are each made adjustable in order that their resistance maybe varied, such adjustment being herein represented as accomplished byvarying the cross-sectional area of the conA ductors. The point at whichthe adjustment is made is in a line crossing the axis of the needle andrunning at right angles to the lines of force of the permanent magnetAThese magnetic conductors present two paths for the lines of forcearound the needle, which may be varied by adjustment, and they alsoserve as a shield for the needle as against external magnetic inluencesFigure 1 shows in front elevation an electric-current-measuringinstrument embodying this invention. Fig. 2 is a detail showing a sideview of one of the pole-pieces and parts connected thereto. Fig. 3 is adetail 55 showing a frontview of said pole-pieces and partey connectedthereto. Fig. 4t is a detail showing an end view of the pole-pieces andparts connected thereto. Figs. 5 to 8 are details showing the partsforming the cores on 6o which the coils are mounted and the chamberwhich contains the magnetiz'ed needle, and Fig. 9 is a moditied form ofsupport for the coils and chamberV for the needle.

d represents the permanent magnet, and a a2 its ple-pieces, which, asherein shown, are represented as oblong plates. The polepieces arebridged together by magnetic conductors at each end. The magneticconductors are made alike, or substantially so, and, 7o as herein shown,each consists of two pins d3 a4, swiveled or pivotally connected at oneend respectively to the pole-pieces, the opposite ends of said pinsbeing made so as to overlap each otherat a point substantially midwaybetween the two pole-pieces. These magnetic conductors are regulated invarious degrees by moving the parts a3 d4 more or less relatively toeach other into and out ofa straight line, as indicated by dotted lines,8o Fig. 4, thereby varying the cross-sectional area of the conductorsand correspondingly increasing or decreasing the resistance. Thesemagnetic conductors unite the poles of perA manent magnets, giving twopaths for the lines of force around the needle and serve as a means ofregulating the amount of lines of force passing through the needle.

b b represent the cores for the conductingcoils 'c c,and said cores aremade of nonmag- 9o netic material and disposed in alinement, and betweensaid cores a chamber is provided for the magnetic needle d, the walls ofwhich are formed integral with said cores b b. The cores b b and partsconnected thereto, which form the chamber for the needle d, may bedivided longitudinally in two parts, (see Figs. 5 to 8,) and said parts,which may be simply castings, will be secured together by screws 2 orotherwiseA Referring to Fig. 7, one of the Ioo parts, as h, is shown,which consists of a substantiallyyrectangular piece of metal having alateral projection 7L' at each side substantially midway its length andhaving an oblong recess h2; and, referring to Fig. 8, the

other part, as h3, is shown, which is similarly constructed, having alateral projection h4 at each side and having an oblong recess 72,5, andalso having an opening h6, which communicates with the chamber formed bythe two oblong recesses h2 h5. Referring to Fig. 9, the cores are shownas made integral with the intermediate piece, and the latter is boredout to present a chamber for the needle.

The needle d is secured to a shaft or spindle d', mounted on a suitablestep d2 and having its upper end bearing in a plate d3, secured to thescrews 2, and to said shaft or spindle a hand or pointer d4 is secured,which is adapted to travel over a suitable dial d5. (Shown in Fig. l.)

The wires leading from the conductingcoil c are connected to theterminal posts e e, which are adapted to be connected to the Wirecarrying the current to be measured.

I claiml. In an electric-eurrent-measuring instrument, a permanentmagnet having its poles bridged together by two magnetic conductors,combined with a m agnetized needle contained in the magnetic field, andinclosed by said magnetic conductors, a pointer carried by said needle,and coils of wire adapted to be connected with the Wire carrying thecurrent to be measured also contained in said magnetic field, andinclosed by said magnetic conductors, substantially as described.

2. In an electric-current-measuring instrument, a permanent magnethaving its poles bridged together by two adj ustable magneticconductors, combined With a magnetized needle contained in the magneticfield, and inclosed by said conductors7 a pointer carried by saidneedle, and coils ot' Wire adapted to be connected with the Wirecarrying the current to be measured also contained in said magnetic eldand inelosed by said magnetic conductors, substantially as described.

3. In an electric-current-measuring instrument, a permanent magnethaving its poles bridged together by two adjustable magnetic conductors,combined with a magnetiz'ed nee die contained in the magnetic eld andinclosed by said conductors, a pointer carried by said needle, and coilsof wire 4adapted to be connected with the Wire carrying the current tobe measured also contained in said magnetic field and inclosed by saidmagnetic conductors, the points of adjustment of'said magneticconductors being in a line crossing the axis of the needle shown and atright angles to the lines of force of saidpermanent magnet,substantially as described.

In testimony whereof I have signed my name to this specication in thepresence of two subscribing Witnesses.

NATHAN H. SUREN.

Vitnesses:

B. J. NoYEs, H. B. DAVIS.

